I have two 1x12" cabinets. Each has two, 8 OHM speakers (Retro 30)
Cabinet #1 has two jacks that are wired parallel.
Cabinet #2 - I tried to wire each jack separately. One jack is wired tip to + of speaker and sleeve is wired to - of speaker. The othe jack I wired opposite; tip to - of speaker and sleeve to - of speaker.
By plugging in a cable from cabinet #1 to cabinet#2 with the parallel wired jack on cabinet #2 I measured approximately 4 ohms.
However, I thought by plugging cabinet #1 into cabinet #2 using the reverse wired jack on cabinet #2 that I would get series wiring resulting in 16 OHMS.
I still measured approximately 4 OHMS. Why did this not work? Must speakers be wired DIRECTLY to each other to achieve parallel or series wiring?
Hi ... all you actually acomplished is wiring your two cabs out of phase with each other ... which would sound prety awful!
It's a bit tricky to do a series wiring job with individual cabs. Here is a pic of how two speakers are wired in series ... do your own search to find plenty more.

Hi, I am trying to do this too. Did you have any luck with yours? I can obviously do the same in parallel but I need to be able to wire in series across two cabs.